The factors responsible for developing a mature homeostatic control of glucose metabolism are under investigation. Newly born lambs and puppies are being studied by isotopic dilution techniques with glucose- C-14 and glucose-2-T for determining basal, fasting hepatic glucose output and peripheral uptake. The hormones, insulin and glucagon will be evaluated as well. Steady state infusions of exogenous glucose at 6 milligrams/kg/min will be given until stable glucose levels are achieved at which time repeat isotope dilution studies will be done. The role of exogenous insulin in achieving sensitive hepatic control will be evaluated. Similar studies are planned for newborn human infants utilizing glucose-C13. Techniques for isolation, purification and combustion of blood glucose are under development. Dr. Susa is continuing his studies of the characterization of a ferrous in ion protein activator of the key gluconeogenic enzyme phosphoenol pryuvate carboxykinase. The developmental changes in this factor will be evaluated.